This invention relates generally to contactless switches, and more particularly, to a contactless inductive proximity switch having an oscillator formed with an oscillator coil, the oscillator coil being contained within a cup core and covered by a ceramic portion.
German Petty Pat. No. 7,307,974 describes a contactless inductive proximity switch having a protective cap formed of an oxide ceramic material. The bottom surface of the proximity switch is relatively thin and disposed entirely within the core of a cup, in an inverted position. The bottom surface is made thin so that the response range of the proximity switch is not excessively reduced. The response range, however, is nevertheless reduced as a result of the cup core surfaces being covered by the ceramic material.
German Reference DE-OS No. 26 18 231 describes an arrangement wherein the operator of a two-wire AC voltage proximity switch is protected in the event that the insulation or the housing of the oscillator coil within the switch is damaged. The arrangement described therein prevents the operator from coming in contact with network potential by providing a separate transformer which provides potential isolation. This solution to a safety problem, however, has the disadvantages of being more expensive and subject to transmission losses